PubMed Health⌕ Search

Biomedical subjects

J S Virdi

Publications and source records attributed to J S Virdi.

At least 19 recordsLinked to original sources
PubMed2004

Detection and assay of beta-lactamases in clinical and non-clinical strains of Yersinia enterocolitica biovar 1A.

OBJECTIVES: To detect beta-lactamases (A & B) and extended-spectrum beta-lactamases (ESBLs) in clinical and non-clinical isolates of Yersinia enterocolitica biovar 1A, and to determine their activity in the presence of specific lactamase inhibitors. METHODS: The presence of beta-lactamases and ESBLs was detected by disc diffusion in 219 (36 clinical, 183 non-clinical) isolates. beta-Lactamase activity was assayed spectrophotometrically in all 36 clinical and 10 representative non-clinical isolates using nitrocefin as the substrate. Inhibition of beta-lactamases was studied by clavulanic acid, aztreonam and cloxacillin. RESULTS: Of the 219 isolates, all except two non-clinical isolates indicated the presence of beta-lactamase A (Bla-A) based on the smaller (2-8 mm) radius of the inhibition zone around the ticarcillin disc. Synergy between ticarcillin and co-amoxiclav discs was, however, observed in only 34% of isolates of non-clinical origin. beta-Lactamase B (Bla-B) was found to be consistently positive among all the clinical and non-clinical isolates, as indicated by its characteristic appearance of flattening of the zone of inhibition around the cefotaxime disc adjacent to an imipenem disc. Bla-B was induced more strongly in clinical than in non-clinical isolates. Inhibition of enzyme A by clavulanic acid, aztreonam and cloxacillin was found to be similar, whereas enzyme B was inhibited more strongly by aztreonam and cloxacillin. None of the isolates showed the unequivocal presence of ESBL. CONCLUSION: This is the first report on beta-lactamases of Yersinia enterocolitica biovar 1A from Asia. Y. enterocolitica biovar 1A expressed both Bla-A and Bla-B. Heterogeneity was, however, discerned in the expression of Bla-A and by induction of Bla-B among clinical and non-clinical isolates of Y. enterocolitica biovar 1A.

Animals↗
PubMed2003

Emerging water-borne pathogens.

Emerging water-borne pathogens constitute a major health hazard in both developed and developing nations. A new dimension to the global epidemiology of cholera-an ancient scourge-was provided by the emergence of Vibrio cholerae O139. Also, water-borne enterohaemorrhagic Escherichia coli ( E. coli O157:H7), although regarded as a problem of the industrialized west, has recently caused outbreaks in Africa. Outbreaks of chlorine-resistant Cryptosporidium have motivated water authorities to reassess the adequacy of current water-quality regulations. Of late, a host of other organisms, such as hepatitis viruses (including hepatitis E virus), Campylobacter jejuni, microsporidia, cyclospora, Yersinia enterocolitica, calciviruses and environmental bacteria like Mycobacterium spp, aeromonads, Legionella pneumophila and multidrug-resistant Pseudomonas aeruginosa have been associated with water-borne illnesses. This review critically examines the potential of these as emerging water-borne pathogens. It also examines the possible reasons, such as an increase in the number of immunocompromised individuals, urbanization and horizontal gene transfer, that may underlie their emergence. Further, measures required to face the challenge posed by these pathogens are also discussed.

Animals↗
PubMed2003

Rhizobacterial diversity in India and its influence on soil and plant health.

The rhizosphere or the zone of influence around roots harbors a multitude of microorganisms that are affected by both abiotic and biotic stresses. Among these are the dominant rhizobacteria that prefer living in close vicinity to the root or on its surface and play a crucial role in soil health and plant growth. Both free-living and symbiotic bacteria are involved in such specific ecological niches and help in plant matter degradation, nutrient mobilization and biocontrol of plant disease. While the rhizosphere as a domain of fierce microbial activity has been studied for over a century, the availability of modern tools in microbial ecology has now permitted the study of microbial communities associated with plant growth and development, in situ localization of important forms, as well as the monitoring of introduced bacteria as they spread in the soil and root environment. This interest is linked to environmental concerns for reduced use of chemicals for disease control as well as an appreciation for utilization of biologicals and organics in agriculture. Indian researchers have studied the diversity of rhizobacteria in a variety of plants, cereals, legumes and others along with assessment of their functionality based on the release of enzymes (soil dehydrogenase, phosphatase, nitrogenase, etc.), metabolites (siderophores, antifungals, HCN, etc.), growth promoters (IAA, ethylene) and as inducers of systemic disease resistance (ISR). Based on such primary screening protocols, effective rhizobacteria have been field tested with success stories from various agroecological zones of the country, as reflected in the control of root- and soil-borne diseases, improved soil health and increased crop yields. Several commercial formulations, mostly based on dry powder (charcoal, lignite, farmyard manure, etc.) have been prepared and field tested, however, problems of appropriate shelf-life and cell viability are still to be solved. Also, inherent in such low cost technologies are the problems of variability in field performance and successful establishment of introduced inoculants in the root zone. In addition, most products available in the market are not properly monitored for quality before they reach the farmer. As a consequence, the acceptance of rhizobacterial formulations in the country is limited. However, several laboratories have now developed protocols for the rapid characterization of effective isolates based on molecular fingerprinting and other similar tools. Also, the use of molecular markers (gus, lux, gfp, etc.) makes it easy to monitor introduced inoculants in situ in soil and rhizosphere environments. The government initiative in integrated nutrient management and pest management systems has provided additional incentives to relate rhizobacterial science to other ongoing activities so that the benefit of this research leads to technologies that are environmentally and socially acceptable.

Agriculture↗
PubMed2001

Arsenite-induced multiple antibiotic resistance phenotype in environmental isolates of Yersinia enterocolitica.

Minimal inhibitory concentrations (MICs) of five antibiotics namely amikacin, gentamicin, tetracycline, ciprofloxacin, and nitrofurantoin for pork isolates of Yersinia enterocolitica increased two- to eightfold after bacteria were grown in the presence of 5 mm arsenite. For Y. enterocolitica isolates obtained from wastewater (sewage effluents), an unequivocal increase in MICs was seen with amikacin and gentamicin. No change was discernible in the outer-membrane proteins after isolates were grown in the presence of arsenite.

Animals↗
PubMed2000

Virulence plasmid (pYV)-associated susceptibility of Yersinia enterocolitica to chlorine and heavy metals.

This study was aimed at elucidating the role of virulence plasmid (pYV) in the susceptibility of Yersinia enterocolitica to bactericidal agents such as chlorine and heavy metals. Plasmid-bearing (pYV+) Y. enterocolitica was less susceptible to the antimicrobial action of chlorine and heavy metals compared with the isogenic plasmidless (pYV-) derivative. This difference was, however, observed only with bacteria cultured at 25 degrees C. pYV-associated susceptibility apart, cells cultured at 37 degrees C were also found to be less susceptible to the antimicrobial action of these agents. The results indicate that the susceptibility of Y. enterocolitica to these agents was influenced both by the presence of the virulence plasmid and the temperature at which the cells were cultured.

Cadmium↗
PubMed2000

Arsenic and cadmium resistance in environmental isolates of Yersinia enterocolitica and Yersinia intermedia.

Environmental strains of Yersinia enterocolitica representing biotype 1A lack virulence plasmid (pYV) and are regarded as non-pathogenic. Though these occupy a diverse range of environmental niches, nothing is known about their resistance to heavy metals. The minimal inhibitory concentrations (MICs) of various metal ions, namely Ag+, Cu2+, Zn2+, Cd2+, As5+, and As3+, for strains of Yersinia enterocolitica (biotype 1A) and Yersinia intermedia (biotypes 1, 2, and 4), isolated from sewage effluents or pork, were determined. All isolates were resistant (MICs 2.5-5 mM) to Cd2+. The MICs of arsenic varied with bacterial strain and the chemical species of the arsenic used. For the majority of the strains, however, it was between 5-10 mM of Na2HAsO4.7H2O and NaAsO2, and 0.625-2.5 mM of As2O3. Except for one isolate, MICs of Ag+, Cu2+, and Zn2+ for these strains were in the range of 0.3-0.625 mM.

Animals↗
PubMed1995

Chitinase production by Streptomyces viridificans: its potential in fungal cell wall lysis.

Streptomyces viridificans was found to be a good chitinase producer among nine species of Streptomyces screened. Minimum levels of constitutive enzyme were observed with both simple and complex carbon substrate. Arabinose doubled the enzyme production amongst the various pentoses and hexoses used with chitin. However, with glucose end-product inhibition and catabolite repression were observed. The enzyme tolerated a wide range of temperature (30-55 degrees C) and pH (3-7.5). Among various divalent cations Mn2+ and Hg2+ completely inhibited the purified enzyme while beta-mercaptoethanol stimulated its activity. Crude and purified enzyme had potential for cell wall lysis of many fungal pathogens tested.

Antifungal Agents↗
PubMed1993

Chemical analysis of post-lithotripsy stone fragments: a critical evaluation.

A scheme for the chemical microanalysis of renal stone fragments recovered from urine voided immediately after lithotripsy has been developed and evaluated. The analytical procedure includes assay of calcium, magnesium, phosphate, oxalate and urate and has been applied to 78 such urine samples. Problems relating to co-existing crystalluria and blood and urine contaminants have been recognised and overcome. However, significant loss of all stone components due to fragment dissolution in urine prior to recovery was found to occur and was investigated. The distribution of stone components found in these analyses was similar to that seen in previous surveys of intact stones.

Calcium↗
PubMed1992

Prognostic value of renal venous involvement in renal carcinoma.

A series of 108 renal tumour nephrectomies carried out between 1975 and 1984 was studied to determine the prognostic statistical significance of the relationship between venous involvement and various pathological features. Tumour size, spread, histological grade and lymph node involvement were compared between V0 tumours (58%), V1 (32%) and V2 tumours (10%). Actuarial 5-year survival rates revealed a poor prognosis with venous involvement (V0 66%, V1 27%, V2 33%). Tumours larger than 10 cm with perirenal spread and of higher histological grade were significantly related to venous involvement. Survival between renal vein involvement and inferior vena caval extension was statistically similar, but it was influenced by tumour size and higher grade. Perirenal spread and nodal involvement were poor indicators.

Adult↗
PubMed1990

Long-term follow-up of intravesical Epodyl therapy for superficial bladder cancer.

The records of 111 patients with multiple superficial grade 1-2 transitional cell tumours of the bladder treated with intravesical Epodyl and followed up for a mean period of 6.4 years were retrospectively analysed. The study showed that 65% of patients responded completely after 12 weekly instillations and 46% of these remained continuously free of disease for 5 years. An initial complete response to therapy and lower pathological grade seemed to indicate a long-term successful response to treatment. In patients who failed to respond by 1 year, further therapy was of no benefit. Clearance of bladder disease by 1 year carried a 14% risk of subsequent tumour invasion by 5 years. This risk increased to 75% in those who failed to respond by 1 year.

Administration, Intravesical↗
PubMed1990

'Solitary' Ta-T1 G1 bladder tumour--history and long-term prognosis.

Natural history of 'solitary', histological grade 1, stage Ta-T1 transitional cell carcinoma of the bladder was studied in 198 patients retrospectively over a period from 1975 to 1987. Three patterns of tumour behaviour were evident. In 56% of patients the tumour did not recur following the initial resection. Twenty-one percent developed recurrences localised to the site of the original tumour. This group became tumour-free by 5 years and remained so thereafter. The remaining 23% continued to produce recurrent tumours up to 10 years at different sites in the bladder. The actuarial percentage of patients who remained continuously free of tumour after the initial resection was 53% at 5 years and 51% at 10 years. The results of this study suggest that cytoscopic follow-up may be discontinued in patients who remain continuously tumour-free for 5 years.

Adult↗
PubMed1989

Effects of aflatoxin on the immune system of the chick.

A decreased antibody response to injected sheep red blood cells and weight losses to the extent of 25-38% were observed in the bursa Fabricii and thymus in chicks fed an aflatoxin diet (10% w/w) for 3 weeks. The immune organs did not show any significant histopathological changes. The antibody titre decreased from day 6 of treatment onward until the 15th day, when the antibody titre had disappeared completely in the test chicks. The body weight gain was also less in test chicks (9.7-37.3%) given test feed or test feed along with Salmonella pullorum in water (10(8) cfu ml 1) in comparison to chicks given toxin-free diet and water after 3 weeks of feeding trials. The disappearing component in the test chicks' liver homogenate was found to be antigenic by immunoelectrophoretic studies.

Aflatoxins↗
PubMed1988

Diagnosis easily missed--upper urothelial tumour.

Four patients with transitional cell tumour of the renal pelvis and ureter who had atypical presentations are described. The associated presenting problem delayed an earlier diagnosis in two patients and facilitated it in the other two.

Aged↗
PubMed1986

Glycosylated haemoglobin (Hb A1) in normal rhesus monkeys (Macaca mulatta).

Glycosylated haemoglobins were measured in 23 healthy juvenile rhesus monkeys by the use of commercially available minicolumn chromatography (Quick Sep., Isolab Inc., Ohio, USA) to establish the normal range. Values obtained (mean +/- 1 standard deviation (SD) 1.57 +/- 0.68%) were significantly lower than that of 17 adult healthy human volunteers by the use of the same method of estimation (mean +/- 1 SD of 5.34 +/- 0.78%).

Animals↗